Arrangement for use in telephony

ABSTRACT

203,293. Ges. f³r Drahtlose Telegraphie. Aug. 30, 1922, [Convention date]. Transmitters and receivers.-In telephonic transmitters and receivers employing an electric arc, a control electrode G is connected to one of the electrodes of the arc. The electrode G, which may be in the form of a ring, renders the arc less stable. The arc is fed by a generator D, and is connected to the line through a transformer E, F. A condenser C, shunted by a resistance W, may be inserted between the winding E and the electrode. Means may be provided for cooling the control electrode G.

Dec. 4, 1928. 1,694,131-

7 E. MAYER ARRANGEMENT FOR USE IN TELEPHONY 7 Filed Ju1 21, 1923 Elvwemtoz EMH. MAYER 85 m QbtoI/nm Patented Dec. 4, 1928.

EMIL MAYER, OF BERLIN, GERMANY, ASSIGNOR 'IO GESELLSCHAF'I. FORDRAHTLOSE TELEGRAPHIE M. B. H. HALLESCHES, OF BERLIN,

GERMANY.

GERMANY, A CORPORATION OF ARRANGEMENT FOR USE IN TELEPHONY.

Application filed July 21, 1923, Serial No.

It is'known that the volume of an electric arc depends upon the strength of current flowing from one electrode to the other. When an alternating current, which, for instance, is an electric copy of speech, is superimposed upon the supplying current of the electric arc, the strength of the current between the electrodes, and, consequently, the volume of the arc, is varied, thereby caus-. ing the arc to reproduce the speech.

In order to obtain comparatively great audibility of the speech, it is necessary that the power of the alternating current superimposed upon the direct current of the electric arc shall be large, and since great ditliculties have been encountered in producing a large alternating current by means of speech, the so-called speaking are has attained no technical importance, although the speaking are, for its quality, indubitably constitutes a good means for reproducing speech.

The present invention provides a new Way of. making the electric are more suitable for the reproduction of speech and further, of

enabling it-to transform speech into alternating currents, that is, to obtain a micro phone effect. The principle of the invention includes passing the electric arc through a conductive and appropriately cooled diaphragm whereby the cross section of the arc is diminished at the diaphragm and the are made more unstable. An alternating voltage produced by speech may be applied to the diaphragm and onepf the arc-electrodes, and the alternating field thereby caused to control the conductivity of the electric arc in the rhythm of speech. The alteration of the volume of the electric are caused by the alteration of current as the conductivity is altered, gives audible response of speech.

The advantage of this method is that it is essentially more sensitive than the methods formerly practiced in the reproduction of speech by the electric arc, and that the consumption of energy between diaphragm and electrode remain small. The ratio of the energy necessary for the controlling of the electric arc to the energy passing through the arc is much more favourable than in the former method.

By suitable adjustment of the diaphragm, which may be readily accomplished by those skilled in the art, it is further possible to use 652,871, and in Germany August so, 1922.

.the electric are as a microphone. In such use of the are it is spoken into, that is, subjected to the pressure of the sound waves themselves, the resistance of the electric are between the diaphragm and the electrodes being altered in accordance with the speech. Accordingly, a corresponding alternating voltage is produced by which the speech is transformed into alternating current energy. The single figure of the drawing is a diagrammat1c representation of a circuit arrangement according to the invention.

In the illustrated arrangement, A and B are the electrodes of the electric arc, G a conductive and suitably cooled diaphragm which is here represented ring-shaped and D a generator supplying the electric arc with direct current. The diaphragm G is connected to the electrode A across the windings E of a transformer in series with a condenser C and a resistance W in parallel.

Under normal operating conditions a small portion of the electron stream flowing between the electrodes A and B will strike the inner side of the ring G and thus cause a current flow in the path A. G. E. C. However, as soon as sound waves strike the are be-- tween the electrodes -A and B they cause a change. in the volume of the are. For example, when no sound impulses reach the arc, the electrons strike in considerable numbers upon the ring G and thus cause a relatively high current flow which builds up a charge on the plates of condenser C, whereupon resistance W, being high, serves to let some current pass over to the electrode A. H owever, when sound energy strikes the arc, the volume of the arc is decreased and, there fore, a lesser number of electrons will strike the ring G, causing less current to flow and the condenser C will then be discharged through the resistance W. By this means the resistance W serves to provide a potential difference across the condenser, permitting it to charge and discharge with the change in the electron stream to the ring caused by the difference in the strength of the sound waves producing a change in volume of the electron stream.

The alternating current produced by speech is passed through the winding F of the transformer as a primary, if the arrangement is to act as a telephone; if, however, it is to act as a microphone, the winding F receives as a secondary the alternating current which is generated by speaking into the electric arc.

Having described my invent-ion, what I claim is:

1. In combination with an arc device, a pair of electrodes a conductive body and a direct current source all in series, said conductive body being in the path of said are, means for varying the resistance of said path in accordance' with sound energy and means controlled thereby for affecting said conductive body.

2. Energy modulating means comprising an electric arc device having a pair of cathodes, a direct current source, a capacity, and a conductive body all in series, said conductive body being in the path of the are means for varying the charge occurring in said capacity in accordance with sound energy which comprises varying the resistance of said are path in accordance with said sound energy thereby varying the electrical energy in said conductive path. a

3. An arc device comprising an anode, a

current source, a cathode, a condenser and a ring shaped electrode all in series, said ring sha ed electrode being positioned so as to be in tlie path of electrons flowing from one of said first two mentioned electrodes to the other, means acting directly upon said are, and comprising sound energy, for varying the number of electrons passing through said ring-shaped electrode and means controlled thereby and including a resistance shunted across said condenser for charging and discharging said condenser in accordance with said sound energy.

4.111 a circuit arrangement of the class described, an electric arc circuit comprising a pair of electrodes, a diaphragm of conductive material interposed between the electrodes, a transformer primary winding, a condenser, and a current source connected all in series, said diaphragm being connected to one of said electrodes through said primary transformer winding and said condenser and a resistance shunted across said condenser.

' EMIL MAYER. 

